Retardation controlled brake



Aug. 24, 1937. E. s. COOK RETARDAT ION CONTROLLED BRAKE A Filed Jan. 26,1955 INVENTOR EARLE S. COOK. BY w.

ATTORNEY Patented Aug. 24, 1937 UNITE STATES PATENT OFFICE RETARDATIONCONTROLLED BRAKE rip-piication January 26, 1935, Serial No. 3,612

13 Claims.

speeds much higher than were formerly common practice. In order toprovide for adequate braking of these high speed trains and vehicles anumber of new type brake systems have heretofore been proposed, each ofwhich has sought to combine a high degree of reliability with simplicityof operation. One example of the heretofore proposed systems is thatdescribed and claimed in the application of Clyde C. Farmer, Serial No.7l2,l53, led February 20, 1934, for an Electropneumatic brake. A featurefound in this and other similar systemsY is that a control valve deviceis provided on each car in the train, and eachV control valve device hasembodied therein certain electrically operated valves under the ,5control of a retardation controller device on the head end or controlcar.

The retardation controller device controls these valves throughout thetrain in a manner such that the rate of retardation produced by brakingis not permitted to exceed a chosen maximum value, which in the majorityof cases will not result in wheel sliding.

The retardation controller device employed is most generally operable tolimit the maximum permissible rate of retardation to one maximum ...jvalue. A disadvantage of thus limiting the rate of retardation to onemaximum value is that the stop may be too abrupt at the end and therebycause some discomfort to passengers, as well as increasing the danger ofproducing damaging d shocks throughout the train. It is desirable thatmeans be provided for reducing the maximum rate of retardation at theend of the stop so that the abruptness of the stop, and shocks, may beeliminated.

It is therefore a principal object of the present invention to provide abrake system for high Speed vehicles and trains in which means areprovided for limiting the maximum rate of retardation due to braking andin which the degree of braking is reduced near the end of thedeceleration period, so that a lower than maximum rate of retardationwill result and a smoother stop thereby accomplished.

A further object of the invention is to provide 3 a brake system oi thischaracter in which means are provided for insuring a predeterminedapplication of the brakes upon faulty operation of the retardationcontrolling means, the degree of application thus eiected beingsuflicient in all cases to bring the train or vehicle to a stop.

Yet further objects, includingla novel arrangement of and utilization ofspecific apparatus, Will Vbe more apparent from the followingdescription,

which is taken in connection with the single gure of the attacheddrawing showing one form that the invention may take.

Considering this form of the invention briefly at first, it will be seenthat it has been shown as applied to one car of a train only, but aswill hereinafter be pointed out, by the duplication of some of the partson succeeding cars a complete train braking system results.

In the embodiment shown, I have provided a control valve device I0 forcontrolling the supply of fluid under pressure to a brake cylinder I2.The control valve device I0 is operable either by straight air operationor by automatic operatio-n, as these terms are commonh7 known in theart.

For controlling applications of the brakes, both by straight airoperation and by automatic operation, I have provicled a brake valvedevice I4.

For limiting the rate of retardation produced by braking to a maximumvalue, I have provided a retardation controller device I6.

For reducing the degree of braking at the end of the decelerationperiod, so as to make a smooth stop, I have provided a pneumatic switchdevice I8 and a release by-pass magnet valve device 20.

For insuring an application of the brakes sufficient to stop the vehicleor train upon faulty operation of the retardation controller device I6,or upon energization of the associated control circuits at unintendedtimes, I have provided a governor valve device 22 and a cut-off by-passmagnet valve device 24.

Considering now these devices more in detail, the control valve devicecomprises an emergency valve section 26, an inshot valve section 28, anda magnet valve section 30.

The emergency valve section 26 is embodied in a casing provided with aslide valve chamber 32 and a piston chamber 33. Disposed in the slidevalve chamber 32 is a slide valve 34, and disposed in the piston chamber33 is a piston 35 having a stem 36 with collars 31 secured thereto forengaging the slide valve 34 and for moving it coextensive With movementof the piston 35. A spring 38 urges the piston 35 upwardly to a biasedposition.

The slide valve chamber 32 is in constant communication with anemergency reservoir 40 by way of pipe 42. The piston chamber 33 isconnected to an emergency pipe 43, and when the piston 35 is in itsupper or biased position a feed groove 44 provides a chargingcommunication between the piston chamber 33 and the slide valve chamber32.

The inshot Valve section 28 is embodied in a casing having a valvechamber 4S in which is disposed a ball valve 4l. The ball valve `4'1 isurged toward an unseated position by a stem 48 associated with a piston49 urged upwardly by a spring 50. The ball valve 41 is adapted to beseated when fluid pressure in piston chamber 5l reaches a predeterminedvalue, as for example l pounds per square inch, and has thus actuatedthe piston 49 downwardly.

Secured to the inshot valve section 28 is a safety valve device 52. Thissafety valve device is preferably of the type commonly employed inconnection with fluid pressure brake systems, and its function, as iswell known in the art, is to prevent the release of pressure from thevolume connected thereto below a predetermined value. For the purpose ofthis disclosure, and by way of illustration, it will be assumed that thesafety valve device is set to retain a pressure in the volume connectedthereto slightly above that which actuates the inshot piston 49downwardly far enough to seat the ball valve 41. The purpose of thiswill appear more fully presently.

`The magnet valve section 30 is embodied in a casing having disposedtherein a cut-off valve 54 and a release valve 56. The cut-off valve 54is urged toward an unseated position by a spring '1, and when inunseated position permits fluid under pressure to iiow from a lowerchamber 58 to an upper chamber 59. The valve 54 is adapted to beactuated to seated position by action of an electromagnet in tlieupperpart of the casingfwhich whenenergized actuates the valve -downwardly tocut off communication between the two chambers 58and 59.

The release valve 56 is adapted to be urged toward seatedposition by aspring 60, and toward unseated position by action of anotherelectromagnet inthe upper part of the casing, which when energizedactuates the valve downwardly. When the release valveA 515- is unseated,a communication is established between a lower chamber 6| and an upperchamber 62, which is in communication with the aforementioned safetyvalve device 52y by way of passage 63.

Therelease by-pass magnet valve device and the cut-off by-passmagnetvalve device 24 are substantially duplicates, each being embodied in acasing provided witha valve 95 urged toward a seated position by aspring 06 and toward an unsera'atedy position` by action of anelectromagnet which when energized actuates the valve downwardly.

The pneumatic switch device I8 is embodied in a casing having a pistonchamber 6l in which is disposed a piston 68 urged downwardly by a spring69. The piston 68 is'providedwith a stem 10 which has secured theretoand insulated therefrom a contact 1|, which is adapted to engageandbridge stationary contacts T2 when the piston 68 is in its lowermostposition.

The retardation controller device It` may be one of a large number oftypes, and for that reason I have indicate-d in diagrammatic form` onlya'pendulum type comprising a pendulum 14 pivotally'secure'd at 15 to asupporting structure 'I6 and so mounted on the vehicle as to be swung tothe left during deceleration of the vehicle when the brakes are applied.Secured to and insulated from the pendulum 14 is a contact 11, which isadapted to successively engage a first stationary contact 18 and asecond stationary contact 19. A spring is arranged to oppose movement ofthe pendulum to the left.

When the `brakes are applied and the vehicle decelerates, the pendulum14 swings to the left under a force of inertia proportional to the rateof deceleration. It will therefore be obvious that the movable contact'H will engage the rst stationaryvcontact '18 at one rate ofretardation, and will then engage the second stationary contact 19 at aslightly higher rate of retardation. It is to be understood that the twostationary contacts 18 and 19 are provided with sufficient resiliency topermit this successive engagement.

The governor valve device 22 is embodied in a casing having a piston 82disposed in a piston chamber 83 and a second piston 84 disposed in asecond piston chamber 85. The two pistons 82 and 84 are joined by a stem86 having collars 81 thereon adapted to engage and move a slide valve 88coextensive with movement of the two pistons. The chamber 89 establishedbetween they two pistons is in communication with the piston charm,- ber83 by way of a port 90 in the piston 82, and is also in communicationwith the piston chamber by way of port 9| in the piston 84.

Disposed in a lower part of the governor valve device casing is a valve93 for controlling communcation between the piston chamber 85 and theatmosphere, and another valve 94 for c ontrolling communication betweenthe piston chamf ber S3 and the atmosphere. The valve 9,3 is urgedtoward unseated position by a spring 95, and is adapted to be urgedAtoward a seated position by movement of a movable abutment 96 to theright,

the movable abutment having a stem 91 adapted to engage the valve 93.The movable abutment 96 is normally urged toward the left by a spring98, and is adapted to be actuated to the right by supply of fluid underpressure to` a chamber 99. which acts upon a diaphragm |00 to urge themovable abutment to the right.

The valve 94 is urged toward seated position by a spring |02, and isadapted to be urged toward` unseated position by a second movableabutment |03 when actuated to the left. The movable abutment |03 ispositioned to the right by a spring |04, and is adapted to be urged tothe left by the supply of fluid under pressure to a pressure chamber|05, which acts upon a diaphragm |06 to urge the movable,v abutment |03to the left so that its stem lill engages the valve 94.

The brake valve device I4I is shown as being of the rotary type, but anyother type performing the same functions may be employed. The rotarytype shown comprises a casing dening a rotary valve chamber |08 havingdisposed therein a rotary valve |09 held upon its seat by a spring I I0.The rotary valve chamber |08 is in constant com munication with a feedvalve device by way of pipe and passage H2. The feed valve device isconnected to a main reservoir II3, and functions to maintain asubstantially constant pressure of the fluid supplied from the reservoir||3 to the rotary valve chamber |08.

The. rotary valve |09 is adapted to be rotated upon movement of thebrake'val've handle |74, to control communications to be hereinaftermore fully described.

The operation of this embodiment of my invention is as follows:

When the vehicle or train is running, the brake. Valve handle |I4 ismaintained in release position, where the rotary valve |69 maintains theemergency pipe 43 connected to the feed valve device I I I, by way ofport IIB in the rotary valve and the rotary valve chamber I |18. Thepressure in piston chamber 33 of the emergency valve section 26 istherefore maintained at feed valve pressure and the piston 35 is held inits upper or biased position. The emergency reservoir 40 is thus chargedfrom the emergency pipe 43, by way of the charging groove 44, slidevalve chamber l5 32, and pipe 42.

The other parts of the apparatus shown will be substantially in thepositions indicated in the drawing.

If now it is desired to effect an application of the brakes by straightair operation, the brake valve handle II4 is turned to the positionwhere straight air pipe l I3 is disconnected from exhaust port ||9through cavity |25 in the rotary valve |09, and to whe-re both thestraight air pipe |13 and emergency pipe 43 are open to the rotary valvechamber m8. Fluid under pressure then flows from the feed valve device|I| to the brake cylinder I2, through a communication including pipe andpassage II2, rotary valve chamber |68, straight air pipe H8, passagesl2| and |22 and cavity |23 in the emergency valve section 26, ball valvechamber 46, past the unseated ball valve 41, and through pipe andpassage I 'J4 leading to the brake cylinder.

When the pressure of the fluid thus iicwing to the brake cylinderreaches approximately l0 pounds, the inshot piston 49 will be actuateddownwardly far enough to permit ball valve 41 to close. Thereafter,fluid flows to the brake cylinder I2 from the ball valve chamber 46through passage |25, chamber 58, past the unseated cutoff valve 54,chamber 59, pipe and passage |26, pipe and passage |21, and from thenceby way of the aforementioned pipe and passage |24. It will thus be seenthat when the inshot ball valve 41 closes fluid flows thro-ugh a by-passcommunication through the magnet valve section 3B.

The inshot valve section 23 is provided to insure that a predeterminedbrake cylinder pressure is so quickly established, so as to take up allslack in the brake rigging and apply the brakes with a predeterminedlight braking force.

If a maximum degree of braking is desired, the brake valve handle II4 isleft in the straight air braking position. As the brake cylinderpressure builds up and the train decelerates, a rate of re tardationwill be reached at which the retardation controller pendulum 14 will beactuated fan enough tothe left to cause contact 11 to engage ('.ocontact 18. When this takes place, the cut-off electromagnet in themagnet valve section 313,

and the electromagnet in the cut-off by-pass magnet valve device 24,will be energized from a battery |29 through a circuit including,conduc- V tor |30, contacts 11 and 18, and conductor |3|, the returncircuit to the battery being by way of ground connections |32 and |33.

The cut-off valve 54 will then be seated to cut oif the flow of fluidfrom the feed valve device I I to the brake cylinder, and the cut-01Tby-pass valve 65 will be unseated to establish communication betweenchamber 58, and feed valve device III, to chamber 89 in the governorvalve device ,.5 22. However, as will appear more fully presently, thegovernor valve device 22 performs no useful function at this time.

If now the rate of retardation should increase to the point wherependulum 14 swings far enough to the left for contact 11 to engagecontact 19, the release electromagnet in the magnet valve section willbe energized from the battery |22, through a circuit including conductor|36, contacts 11 and 19, and conductor |34, the return circuit to thebattery being also by way of ground connection |32. Release valve 56 isthen actuated to unseated position, and fluid under pressure is releasedfrom the brake cylinder I2 to the atmosphere, through a communicationincluding pipe and passage |24, passage |21, choke |35, which restrictsthe rate of release, chamber 6|, past the unseated release. valve 5S,chamber 62, passage 63, and safety valve device 52.

As soon as sufficient reduction in brake cylinder pressure has beenproduced by the release of huid from the brake cylinder to cause adecrease in the rate of retardation, the pendulum 14 swings to the rightto disengage contact 11 from contact '|',`whereupon the releaseelectromagnet will be deenergized and release valve 56 again seated tocut off the release of fluid under pressure from the brakecylinder.

l'f the rate of retardation should again increase, the cycle justdescribed will be repeated by the re tardation controller device, sothat a rate of retardation substantially between that which causesengagement of contact 11 with contact 18 and that which causesengagement of contact 11 with contact 19 will be maintained throughoutthe greater part of the deceleration period.

Now when fluid underv pressure was initially supplied to the brakecylinder, .it also ilows to chamber 61 in the pneumatic switch deviceI8, by Wa-y of pipe |42. When thepressure in chamber G1 exceeds somepredetermined value, as for eX- ample 25 or 30 pounds per square inch,the piston 58 will be actuated upwardly and movable contact 1t willdisengage from stationary contacts 12.

The contacts 1| and 12 control energization of the release by-passmagnet valve device 2li from battery |29. It will be noted that a pushswitch E35, having contacts |31 held open by a spring |33, is located inthe circuit to this magnet valve device. This switch device is optionaland is provided for a purpose which will ybe discussed later. For thepresent, contacts |31 will be assumed to be closed, but it is to beunderstood that the function performed by these contacts is not whollyessential to the generic aspects of the invention.

Therefore, with the contacts |31 of push switch |35 closed, as thepressure in the brake cylinder i2 decreases due to operation of theretardation controller device I6, a point will be reached, near` t ieend of the deceleration period, when the pressure in the chamber 51 willhave been reduced below 25 or 30 pounds per square inch, and piston 65will move downwardly to again cause engage-- ment of contact 1| withcontacts 12. When this takes place the electromagnet in the releasebypass magnet valve device 2E will be energized from the battery |29,through a circuit including conductor 14|, contacts |31, conductor |42,contacts 1l and 12, and conductor |43, the return connection to thebattery being by way of ground connection |44.

The valve |55 will then be actuated to unseated position, and the brakecylinder I 2 will be connected directly to the safety valve device 5?.,through a communication including pipe and passage |24, pipe and passage|21, pipe |40, past the unseated valve 65, pipe |45, and passage |46.The pressure in the brake cylinder will thus be reduced to the settingof the safety valve device, and this setting, which is above that whichwould permit the inshot ball valve 41 to unseat, is preferably lowenough so that the degree of braking is reduced to the point where therate of retardation produced is considerably below that maintained bythe retardation controller device. The vehicle or train will thus bebrought to a smooth stop, free of shock.

It should be evident that by reducing the rate of retardation at the endof the deceleration period that the stop will be lengthened somewhat. Ifthe operator should desire to make a stop in the shortest possibledistance, to prevent collision, to make a spot stop, or for otherequally important reasons, he permits contacts |31 of push switch |36 toremain open, thereby maintaining the circuit to the release by-passmagnet valve device 29 open so that the brake cylinder is not connecteddirectly to the safety valve device 52. The maximum rate of retardationwill thus be maintained throughout the entire deceleration period.

If it is desired to effect an application of the brakes by automaticoperation, the brake valve handle ||4 is turned to the automaticposition, where the rotary valve |99 blanks the straight air pipe i |8and where cavity |25 connects emergency pipe 43 to the atmosphere by wayof exhaust port 9. When the emergency pipe 5:3 is thus vented to theatmosphere, the over-balancing pressure in slide valve chamber 32 of theemergency valve section 35 will cause the piston 35 to be moved ydownwardly to its lowermost position. In this p0- sition, slide valve 34blanks passage |2| and connects passage |22 to the emergency reservoir48. Fluid under pressure then flows from the emergency reservoir to thebrake cylinder by way of the communication heretofore described inconnection with a straight air application.

If the brake valve handle 4 is left in the automatic position, the partsthen function as before described to limit the rate of retardation tothat provided for by the retardation controller device.

In a similar manner, if it is desired to make a smooth stop, theoperator depresses the push Switch |35, and the pneumatic switch device|8 and release by-pass magnet valve device 20 function as beforedescribed to reduce the degree of braking at the end of the decelerationperiod.

If at any time there should be false energization of the conductor 3|leading to the cut-off bypass magnet valve device 24, as would happenupon faulty engagement of contact 11 with contact 18, or upon faultycrossing of conductors |3| and |30, cut-off valve 54 in the magnet valvesection 39, will be actuated to seated position. Therefore, when thebrake valve handle is turned to application position, the brake cylinderpressure would be limited to that which causes the inshot valve 41 toseat, which is too low to stop the vehcle or train, were it not for thecut-off by-pass magnet valve device 24 and governor valve device 22. Themagnet valve device 24 is at this time also energized to unseat ritsvalve 65, to supply fluid under pressure to governor valve devicechamber 89.

As fluid flows to chamber 89 it passes through port 99 in piston 82 tochamber 83, and also through port 9| into piston chamber 85. 'Ihe pistonchamber 85 is at this time in communication with the atmosphere, due tovalve 93 being unalready in this position. In this position, slide?.

valve 88 connects the brake cylinder |2 to the slide valve chamber 89,and to feed valve device by way of port |49, and pipe and passage |58.At the same time, communication is established between chamber 89 anddiaphragm chamber |85, by'z.D

means of passage |5|.

Fluid under pressure flo-wing to chamber 89 also flows by way of passage|52 to diaphragm chamber 99. When the pressure in chamber 99 reachessome predetermined low value, as for eX-- ample between 8 and 10 poundsper square inch, diaphragm |89 is actuated to the right, to causeseating of valve 93. Seating of this valve however does not disturb theposition of the vtwo pistons 82 and 84, as the pressures on either sideof these two pistons are balanced.

However, as the pressure in chamber 89, and diaphragm chamber |05,continues to increase, when the pressure reaches approximately 410,Ipounds per square inch, diaphragm |95 will be actuated to the left tocause unseating of valve 94. Unseating of this valve vents chamber 83 tothe atmosphere, and the overbalancing pressure in chamber 89 actuatespistons 82 and 84 to the left. Slide valve 88 then cuts off thecommunication to the brake cylinder through port |49, and connectsdiaphragm chamber |05 to exhaust port |54, through cavity |55. Diaphragm|95 then moves to the right to cause seating of the valve 94, to preventundue loss of fluid under pressure, which would take place through port98 in piston 82 were not valve 94 seated.

It will thus be seen that the governor valve device '22 functions duringa brake application, when conductor |3| is falsely energized, to.establish a brake cylinder pressure of approximately 49 pounds persquare inch, which pressure is used by way of illustration to indicatesome value of pressure sufficient to bring the vehicle or train to astop.

When no faults exist in the system, and cut-ofl by-pass magnet valvedevice 24 remains deenergiz-ed, fluid under pressure supplied to thebrake cylinder I2 also flows by Way of pipe |58 to the governor valvedevice 22. If the slide valve 88 is in the position shown in thedrawing, then fluid will flow through port |49 to chamber `89 and thevalve device will loperate as before described to move the slide valveto the left when the brake cylinder pressure reaches 40 pounds persquare inch. This will not affect the brake cylinder pressure, which iscontrolled by .either the brake valve device |4 or by the cooperativefunctioning of the magnet valve `section 3.0 and the retardationcontroller device I5.

When the retardation controller device during normal operation energizesthe electromagnet Aof .cut-off valve 54 -it also energizes the cutoifby-pass mag-net valve Vdevice 24, but since the governor slide valve -88is already in its left hand position the brake cylinder pressure isstill unaffected.

In the adaptation of the embodiment described to a train, al1 of theparts shown in the drawing will of course be supplied on the head end orcontrol car. On succeeding cars a control valve device ||l, an emergencyreservoir 48, a cut-off by-pass magnet valve device 24, a governor Valvedevice 22, a switch device yH3 and a release by-pass LII magnet valvedevice Eil may be supplied on each car in connection with the brakecylinder, or brake cylinders, oi that car.

From the foregoing description it will be evident that I have provided abraking system in which the maximum rate of retardation is limited to apredetermined value, which may be reduced at the end or the decelerationperiod so as to make a smooth stop. ln addition, I have provided meansoperative upon initiating a brake application while false energizationof certain of the retardation controller circuits exists to insuresuilicient braking for bringing the train to a stop, so that the faultmay be cleared before damage results.

`brake cylinder, means for effecting a supply of fluid under pressi e tothe brake cylinder, a retardation controller device operated accordingto the rate of retardation of the vehicle, means responsive to operationof said retardation controller device at a chosen rate ci retardationfor controlling fluid under pressure supplied to the brake cylinder,means operated upon a decrease in brake cylinder pressure below apredetermined value `for further decreasing the brake cylinder pressureto a lower value, and means rendered operative upon faulty operation ofsaid retardation controller device for establishing brake cylinderpressure higher than said predetermined value.

2. In a vehicle brake system, in combination, a brake cylinder, meansfor effecting a supply of liui-d under pressure to the brake cylinder, acontrol circuit, means operated according to the rate of retardation ofthe vehicle for connecting said circuit to a source oi current supply,means responsive to energization of said circuit for cutting o thesupply to the brake cylinder, means also responsive to energization ofsaid circuit for establishing a .by-pass communication through whichfluid under pressure may flow to the brake cylinder, means operated upona predetermined brake cylinder pressure for cutting oli said supplythrough said by-pass communication, and means controlled by brakecylinder pressure for subsequently effecting a reduction in brakecylinder pressure.

3. In a vehicle brake system, in combination, a brake cylinder, meansfor effecting a supply of fluid under pressure to the brake cylindereither by straight air operation or by automatic operation, means forestablishing a communication having three parallel branch'paths throughwhich iluid under pressure supplied to the brake cylinder news, a irstelectroresponsive means in one of said branch paths for controlling flowthrough that path, a second electroresponsive means in another of saidbranch paths for controlling flouT through that path, pressure operatedvalve means izo the remaining one of said branch paths for controllingflow through that path, said pressure operated valve means beingoperable to close the associated path at a predetermined pressure ofiiuid supplied through said path, a retardation controller device, and

means for controlling said two electroresponsive means according tooperation of said retardation controller device.

4. In a Vehicle brake system, in combination, a brake cylinder, meansfor establishing a, communication through which uid under pressure issupplied to the brake cylinder, means for supplying fluid under pressurethrough said communication, a valve device controlling saidcommunication and operated upon a predetermined ressure of iiuidsupplied through said communication for closing said communication,means for establishing a by-pass communication around valve device,electroresponsive valve means operable when energized to close saidby-pass communication, means for establishing a second Icy-passcommunication around said electroresponsive valve means, a secondelectroresponsive valve means operable when energized to open saidsecond by-pass communication, means for cutting oli the flow of fluidthrough said second bly-pass communication at a pressure higher thansaid aforementioned predetermined pressure, a retardation controllerdevice operated according to the rate of retardation of the Vehicle,means responsive to operation of said retardation controller device at achosen rate of retardation for releasing iiuid under pressurey from thebrake cylinder, and means-responsive to a predetermined low value ofbrake cylinder pressure for establishing a second communication throughwhich fluid under pressure is released from the brake cylinder.

5. In a vehicle brake system, in combination, a brake cylinder, meansfor supplying iuid under pressure to the brake cylinder, a retardationcontroller device operated according to the rate of retardation of thevehicle, means responsive to operation of the retardation controllerdevice for cutting off the supply of fluid to the brake cylinder and forestablishing a communication through which fluid under pressure isreleased from the brake cylinder, means for establishing a secondcommunication through which fluid under pressure is also released fromthe brake cylinder, and electrically controlled means normallymaintaining said second communication closed and operated at a chosenbrake cylinder pressure for opening said communication.

6. In a vehicle brake system, in combination, a brake cylinder, meansfor establishing a communication through which fluid-under pressure issupplied to the brake cylinder, means for controlling opening andclosing of said communication, means for establishing two communicationsthrough which uid under pressure is released from the brake cylinder, anelectrically operated valve device for controlling one of said twocommunications, a retardation controller device for controlling saidelectrically operated valve device, and electrically controlled means`governed by brake cylinder pressure for controlling the other of saidtwocommunications.

'7. In a vehicle brake system, in combination, a. brake cylinder, meansfor supplying iiuid under pressure to the brake cylinder, a retardationcontroller device operated according to the rate of retardation of thevehicle, means responsive to operation of said retardation controllerdevice at a chosen rate of retardation for cutting oit the supply to thebrake cylinder and for establishing a communication through which iiuidunder pressure is released from the brake cylinder, means forestablishing a second communication through which fluid under pressureis released from the brake cylinder, electroresponsive valve meansoperable when energized to open said second communication, contacts forcontrolling energization of said electroresponsive valve means, andmeans responsive to brake cylinder pressure for opening said contactsabove a predetermined pressure and for closing said contacts below saidpredetermined pressure.

8. In a vehicle brake system, in combination, a brake cylinder, meansfor supplying fluid under pressure to the brake cylinder, a retardationcontroller device operated according to the rate of retardation of thevehicle, electroresponsive valve means responsive to operation of saidretardation controller device at one rate of retardation'for cutting offthe supply to the brake cylinder and responsive to operation of saidretardation controller device at another rate of retardation forestablishing a communication through which fluid under pressure isreleased from the brake cylinder, means for establishing a secondcommunication through which fluid under pressure is released from thebrake cylinder, magnet valve means normally closing said secondcommunication and adapted when energized to open said communication, aswitch device responsive to brake cylinder pressure and operable atpressures above a predetermined value for preventing energization ofsaid magnet valve means and operable at pressures below saidpredetermined value to permit energization of said magnet valve means,and manually operated means for effecting energization of saidv magnetvalve means when said switch device is closed.

9. In a vehicle brake system, in combinati-on, a brake cylinder, meansfor effecting a supply of fluid under pressure to the brake cylinder, aretardation controller device having two normally open contacts andoperable at one rate of retardation to close one of said contacts andoperable at another rate of retardation to close the other of saidcontacts, a safety valve device, means responsive to closing of one ofsaid contacts for cutting off the supply of fluid under pressure to thebrake cylinder, means responsive to `-closing of the other of saidcontacts for establishing a communication between said brake cylinderand said safety valve device to release fluid under pressure from thebrake cylinder, means for establishing a second communication from saidbrake cylinder to said safety valve device, electroresponsive valvemeans normally closing said second communication and operable whenenergized to open said second communication, means for energizing saidelectroresponsive valve means, and means for preventing energization ofsaid electroresponsive valve means for brake cylinder pressures above apredetermined value.

10. In a vehicle brake system, in combination, a brake cylinder, meansfor establishing a first communication through which fluid underpressure is supplied to the brake cylinder, an inshot valve device insaid irst communication operable at a predetermined pressure of fluidsupplied through said first communication for closing said firstcommunication, means for establishing a by-pass communication aroundsaid first communication, a retardation controller device having twonormally open contacts and being adapted to close one of said contactsat one rate of retardation and to close the other of said contacts at ahigher rate of retardation, a magnet valve device responsive to closingof said rst contact for closing said by-pass communication, a safetyvalve device, a second magnet valve device responsive to closingA ofsaid second contact for establishing a communication between said brakecylinder and said safety valve device, means for establishing a second'communication from said brake cylinder to said safety valve device, anormally deenergized magnet valve device in said second communicationand operable when energized to open said communication, a circuit forenergizing said second magnet valve device, and a switch device in saidcircuit responsive to brake cylinder pressure and operable to open saidcircuit for brake cylinder pressures above a chosen value and to closesaid circuit for brake cylinder pressures below said chosen value.

1l. In a vehicle brake system, in combination, a brake cylinder, meansfor establishing a rst communication through which fluid under pressureis supplied to the brake cylinder, means for supplying fluid underpressure through said first communication, an inshot valve device insaid rst communication and operable at a predetermined pressure forclosing said communication, means for establishing a by-passcommunication around said inshot valve device, means for controllingflow of fluid through said by-pass communication and operable to cut oisaid iiow at a pressure higher than said predetermined pressure,electroresponsive valve means operable to close said oy-passcommunication when deenergized and to open said by-pass communicationwhen energized, and means for controlling energization anddeenergization of said electroresponsive valve means.

l2. In a vehicle brake system, in combination, a brake cylinder, meansfor establishing a com; munication through which fluid under pressure issupplied to the brake cylinder, an inshot valve device in saidcommunication operable at a predetermined pressure to close saidcommunication, means for establishing' a by-pass communication aroundsaid first communication, a magnet valve device operable when energizedto close said bypass communication, means for establishing a secondby-pass communication around said first by-pass communication, a secondmagnet valve device operable when energized to open said second by-passcommunication and when deenergized to close said second by-passcommunication, means for energizing both of said magnet valve devices,and a governor valve device in said second by-pass communicationoperable to cut off ow of fluid through said second by-pass'communication when the pressure of said fluid exceeds a predeterminedvalue.

13. In a vehicle brake system, in combination,

l a brake cylinder, means for establishing a communication through whichfluid under pressure is supplied to the brake cylinder, means forclosing said communication, means for establishing a by-passcommunication around said first communication through which fluid underpressure is also supplied to the brake cylinder, a magnet valve devicenormally closing said byv-pass communication and operable when energizedto open said communication, means for energizing said magnet valvedevice, a valve controlling flow of fluid through said by-passcommunication, means responsive to a low value of pressure of fluidsupplied through said by-pass communication for positioning said valveto permit flow through said by-pass communication, and means responsiveto a high value of pressure of fluid supplied through said by-passcommunication for positioning said valve to cut off iiow through saidbypass communication.

EARLE S. COOK,

